1. Field of the Invention
The present invention relates to an electrostatic motor which generates a driving force using an electrostatic force and, more particularly, to a film-like electrode member used for the electrostatic motor.
2. Description of the Related Art
There has been developed an electrostatic motor in which each of a stationary member (or a stator) and a movable member is formed from a film-like electrode member including a film-like insulating substrate and a plurality of electrodes arranged thereon, a multi-phase AC power source being connected to each film-like electrode member so as to move the two film-like electrode members relative to each other. As compared to an electric motor using an electromagnetic force, this type of the electrostatic motor does not require a large mass component, such as a magnetic coil or a permanent magnet, and thus can be easily fabricated in a small size, which permits it to be utilized as, e.g., a drive source for a micro-machine.
Japanese Unexamined Patent Publication (Kokai) No. 6-78566 (JP6-78566A) discloses an electrostatic motor provided with a stationary member including an insulating substrate and a plurality of electrodes arranged along a major surface of the insulating substrate at predetermined intervals, and a movable member including another insulating substrate and a plurality of electrodes arranged on a major surface of the insulating substrate at predetermined intervals. In this electrostatic motor, the stationary member and the movable member are assembled together relatively movably in a direction along the major surfaces thereof, with the respective plural electrodes (usually, strip-shaped or line-shaped electrodes) being regularly opposed to each other. In this state, a three-phase AC voltage is applied to, e.g., every three parallel electrodes in the respective sets of electrodes of the stationary member and the movable member, to generate an electrostatic force between the two sets of electrodes due to traveling-wave electric fields having different phases, so that a driving force is generated in the movable member so as to act in a direction of the parallel arrangement of the electrodes (or in the direction along the major surface).
JP6-78566A also discloses a laminated configuration constructed by alternately stacking plural stationary members and plural movable members, so as to provide plural sets of stationary members and movable members, each set having opposing electrodes, for the purpose of increasing the output power of a single motor. JP6-78566A further discloses a linear electrostatic motor in which the movable member linearly moves relative to the stationary member, and a rotary electrostatic motor in which the movable member rotates about an axis relative to the stationary member.
In the laminated configuration, in general, the plural stationary members are arranged to be stacked at predetermined intervals with spacers interposed therebetween, the plural movable members are arranged to be stacked at predetermined intervals with other spacers interposed therebetween, and the stack of the stationary members and the stack of the movable members are assembled together in such a manner that the respective stationary members and the respective movable members are alternately arranged. Each spacer is dimensioned to have a thickness slightly larger than the thickness of the insulating substrate of the stationary or movable member, in order to maintain a required small clearance between the major surface of the stationary member and the major surface of the movable member. Further, each spacer may incorporate therein a connection conductor, such as an electrically conductive rubber, an electrically conductive spring or an electrically conductive pin, for electrically connecting the plural stationary members with each other or for electrically connecting the plural movable members with each other.
In the conventional electrostatic motor having the laminated configuration, as described above, in order to maintain the plural stationary members and the plural movable members at respective predetermined intervals, the spacers formed separately from the film-like electrode members of the stationary and movable members are used, and the laminated configuration is provided through an assembling process. Such an assembling process is generally complex and requires skill. For example, in the case where the connection conductor as a resilient member, such as an electrically conductive rubber or an electrically conductive spring, is incorporated in each spacer, a positional deviation may be caused between the stationary member and the movable member in a direction other than the direction of thickness thereof. In this connection, generally in the electrostatic motor, the electrode pitch of the stationary or movable member is about 0.1 to 1 mm. Therefore, the slight positional deviation caused during the assembling process turns into a large error of the fine electrode patterns in the stationary and movable members, which may result in a difficulty in obtaining a theoretical output power. Besides, it is difficult to visually confirm whether the spacers and the connection conductors are accurately arranged between the stacked plural stationary and movable members.